If you need more goals, stick with Williams. If you need more assists, and PPP pick up Hemsky. Williams is more durable than Hemsky though, so if you go with him expect to deal with some injury time. They'll both probably finish in the same ballpark o' points, though... 50-60 tops.

I'll stick with Justin Williams. His stat shows that he deserves to be chosen and shouldn't be drop. With him in your team, you'll surely have a great game. One more thing, consider his goal points. That reason alone is enough to keep him.